At present, "allelopathy", which is represented by the phenomenon of promotion of ripening fruits by ethylene released from other ripened fruits, is known and observed in every plant including microorganisms. Nowadays, such a phenomenon is attempted to be applied positively to the growth regulation of plants (H. Molisch: "Der Einfluss einer Pflanze auf die andere Allelopathie", Gustav Fischer Verlag, Jena. 1937), and is practically applied in some cases (E. L. Rice (1984): Allelopathic effects of crop plants on other crop plants. In "Allelopathy" 2nd ed. pp. 41-67, Academic press, Inc.).
As "allelopathy", it was found that if specific kinds of seeds or seedlings are cultured in the presence of cress plant seeds in a Petri dish, then the growth of hypocotyls is promoted, whereas the growth of seedling roots is inhibited (Zasso Kenkyu, 37, 68 (1992); Zasso Kenkyu, 37, 71 (1992)).
However, the substantiality of substance bringing about such "allelopathy" has still not been identified.
"Hydroponics", i.e. a method of growing plants in an aqueous solution with nutrients dissolved, was carried out widely as "water culture" in the old days, and has become a method more frequently adopted owing to the development in plant biotechnology in recent years.
The most important item for carrying out hydroponics is to select a suitable composition to be used for a culture solution.
Typical examples of such culture solutions are Sachs' solution, Knop's solution, Hoagland's solution, etc.
Under the circumstances, the development of hydroponics using a new culture solution has been desired with the aim of establishing more efficient hydroponics.
Bean sprouts, barley malt, etc., are mainly grown legume sprouts in the dark (referred to as "moyashi", hereinafter) and 1 week or so is required for their industrial production. In recent years, it has been conducted to inhibit the growth of roots and remove roots mechanically in the production of moyashi in order to improve their value as commercial products.
It has therefore been desired to develop a method for producing moyashi of enhanced value as a commercial product in higher productivity.
In order to solve the above problem, the present inventors have isolated and identified, from seedlings of cress etc., physiologically active substances bringing about "allelopathy", have succeeded in the synthesis of said substances and derivatives thereof, and have established a new culture method comprising use of a new artificial soil or culture solution, and they have found that said substances can promote the growth of moyashi simultaneously with the growth inhibition of roots, thereby arriving at the completion of the present invention.